Title:
Seismic Retrofit of Octagonal Columns with Pedestal and One-Way Hinge at Base
Author(s):
Nathan Johnson, M. Saiid Saiidi, Ahmad Itani, and Samaan Ladkany
Publication:
Structural Journal
Volume:
102
Issue:
5
Appears on pages(s):
699-708
Keywords:
bridges; columns; reinforced concrete; retrofit; shear
DOI:
10.14359/14665
Date:
9/1/2005
Abstract:
This study focused on the development of retrofit methods for octagonal single column bents with a pedestal and a one-way hinge detail at the pedestal base that are commonly found in bridge construction. Three identical quarter-scale column specimens were built for shaketable testing. One was tested as-built, the others were enhanced with seismic retrofits. The columns were subjected to the 1994 Northridge Sylmar earthquake in the strong direction until failure. Lateral steel of the as-built pedestal was highly deficient, resulting in an undesired pedestal failure. The first of the retrofitted columns was tested with a pedestal extension and a glass fiber-reinforced polymer (GFRP) pedestal jacket. The second was tested with the same retrofit as the first but several of the column bars were severed at the base of the column to reduce plastic shear demand. It was determined that the pedestal retrofit was successful to strengthen the pedestal sufficiently to shift the plastic hinging into the column. The severed column bars lowered shear demand and increased the plastic deformation. Analytical models to determine the shear strength and push-over behavior were evaluated using the test data.